Camera with blur reducing function

ABSTRACT

An exposure start determining section executes exposure start determination to reduce shaking during exposure, on the basis of the output of the shake detecting/computing section. At this time, an exposure start method used in the exposure start determining section is changed in accordance with a change condition set in a condition setting section. For example, in accordance with an exposure start instructing operation (a releasing operation), preparatory operations (such as a mirror-raising operation, a lens stop down operation, etc.) for exposure are executed. When the preparatory operations have finished, the shake detecting/computing section and the exposure start determining section start to operate. An exposure-start-determining-method changing section changes an exposure start determination method used in the exposure start determining means before and after a predetermined period elapses from the start of the shake detecting/computing section and the exposure start determining section.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Applications No. 11-118018, filed Apr. 26,1999; No. 11-118020, filed Apr. 26, 1999; and No. 11-118022, filed Apr.26, 1999, the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

This invention relates to a camera with a blur reducing function, whichcan start a photographing operation (a film exposure operation in thecase of a camera using a film, and an imaging operation in the case of adigital camera) at a time point at which the camera is not greatly shookby hand, and more particularly to a method for determining whether thephotographing operation should be started.

There are, so far, lots of proposals for a camera with a blur reducingfunction, which is adapted to start its exposure operation at a timepoint at which the camera is not greatly shook by hand.

For example, U.S. Pat. No. 5,790,490 proposes an anti-shake camerawherein the level of hand-shake of the camera is detected, and exposureis started when it is determined that the level of shaking is lower thana predetermined value, i.e. that the shake level of the camera issufficiently reduced, thereby preventing (reducing) blurring fromoccurring in a photograph.

The method disclosed in the above US Patent enables reduction inblurring in a photograph. If, however, a long time lag exists due to amechanical operation of, for example, a shutter until exposure isactually executed after it is determined that the level of shakingreduces and hence that start of exposure is allowable, a high blurreducing effect cannot be obtained.

To avoid this, Japanese Patent Application KOKAI Publications Nos.5-204012, 5-204013 and 5-204014, for example, disclose a technique forestimating hand-shaking, and determining on the basis of the estimationresult whether exposure should be started, thereby enhancing the blurreducing effect.

However, to estimate the state of shaking that will occur after apredetermined period, data on the state of shaking at previous timepoints are necessary. Therefore, unless such data is accumulated for apredetermined period, shake estimation cannot be executed, andaccordingly exposure start determination based on the estimation resultcannot be executed. The period required for data accumulation is, forexample, about several tens milliseconds, which leads to a long time lagfor releasing the camera. It is highly possible that a small amount ofshaking will occur during the time lag, and accordingly the photographermay miss the opportunity of starting exposure.

There is one type of photography that is executed while moving a camera.In this photography, shaking or movement inevitably occurs. Therefore,if the anti-shake camera as disclosed in the U.S. Pat. No. 5,790,490 isused for the above photography method, the operation of moving a camerais erroneously determined as shaking. As a result, exposure is hard tostart, which may result in missing the best opportunity for photography.

This disadvantage can be eliminated by turning off the blur reducingfunction or mode. In order to turn off the mode, however,setting/operation for it alone must be done and it is troublesome.

Further, a problem of “shaking”, which occurs in usual photography,exists in a direction differing from that of the movement of a cameraduring photography executed while moving the camera.

In the anti-shake camera disclosed in the US Patent, reduction ofshaking is detected by determining whether or not both shake levels intwo directions have crossed a level of zero (shake velocity is zero; astationary state).

In this technique, exposure is basically started after the level ofshaking reduces, and hence the release time lag may be longer than inthe usual case. The release time lag greatly depends upon theaforementioned predetermined period. Specifically, if the predeterminedperiod is set short, both the shake levels in two directions rarelycross the zero level, resulting in a long release time lag. On the otherhand, if the predetermined period is set longer, it is highly possiblethat both the shake levels in two directions will cross the zero level,and hence that the start of exposure will be determined to be allowable.Accordingly, the release time lag will be short. In this case, however,it is also highly possible that the degree of blurring in an exposedphotograph will be high.

In the system disclosed in the above-described US Patent, basically, ifthe shake level is continuously high, the shake level during exposure isalso high. In light of this, if blurring occurs in a photograph evenwhen exposure timing control is executed to reduce blurring, it isdesirable that the release time lag be short.

Moreover, there is a method in which exposure start determination isperformed at a time point at which the level of shaking is low, and thistime point is determined using a predetermined threshold value insteadof the zero level. Also in this case, the same problem as above willoccur depending upon whether the threshold value is high or low.

BRIEF SUMMARY OF THE INVENTION

The present invention has been developed in light of the above problemsand aims to provide a camera with a blur reducing function for detectinga time point at which the level of shaking is low, thereby startingexposure at this time point, the camera being capable of quicklyexecuting exposure start determination without a long time lag and hencebeing easy to use.

It is another object of the invention to provide a highly usable camerawith a blur reducing function, capable of, without a long shutter timelag, even executing photography while moving the camera so as to obtaina best opportunity for photography.

It is yet another object of the invention to provide a camera with ablur reducing function, in which exposure is allowed when the level ofshaking is low, the camera being operable with a short release time lag.

According to a first aspect of the present invention, there is provideda camera with a blur reducing function, comprising:

shake detecting/computing means for detecting and computing a shakestate of the camera;

exposure start determining means for executing exposure startdetermination to reduce shaking during exposure, on the basis of anoutput of the shake detecting/computing means;

exposure means for executing an exposure operation in accordance with adetermination result of the exposure start determining means;

exposure-start-determining-method changing means for changing anexposure start determination method used in the exposure startdetermining means; and

condition setting means for setting a condition used in theexposure-start-determining-method changing means for changing theexposure start determination method used in the exposure startdetermining means.

According to a second aspect of the present invention, there is provideda camera with a blur reducing function, comprising:

shake detecting/computing means for detecting and computing a shakestate of the camera;

shake estimating means for storing an output of the shakedetecting/computing means and estimating a level of shaking on the basisof the stored output;

shake information stored state monitoring means for monitoring a shakeinformation stored state of the shake estimating means;

exposure start determining means for executing exposure startdetermination to reduce shaking during exposure, on the basis of anoutput of the shake detecting/computing means or an output of the shakeestimating means;

exposure means for executing an exposure operation in accordance with adetermination result of the exposure start determining means; and

exposure-start-determining-method changing means for changing anexposure start determination method used in the exposure startdetermining means, on the basis of a monitoring result of the shakeinformation stored state monitoring means.

According to a third aspect of the present invention, there is provideda camera with a blur reducing function, comprising:

a shake detecting section for sampling shake levels of the camera in atime series manner;

a computing section for receiving a predetermined number of shake dataitems sampled by the shake detecting section in the time series manner,and executing predetermined computation of the shake data items; and

a photography start timing determining section for comparing latestshake data, output from the shake detecting section, with a firstdetermination reference range, and comparing a computation result, whenoutput from the computing section, with a second reference rangedifferent from the first reference range, thereby determining on thebasis of comparison results whether or not photography should bestarted.

According to a fourth aspect of the present invention, there is provideda camera with a blur reducing function including a shake detectingsection for repeatedly detecting a shake state of the camera, and inwhich a shake state of the camera is repeatedly detected in response toa releasing operation for instructing start of photography, andphotography is started at a time point at which shaking is in apredetermined state, comprising:

a determination reference range setting section for setting first andsecond reference ranges which are different from each other;

a shake estimating section for estimating a shake state of the camera tobe obtained after a predetermined period, on the basis of apredetermined number of shake data items detected by the shake detectingsection; and

a photography start timing determining section for comparing latestshake data, output from the shake detecting section, with a firstdetermination reference range until estimation information is outputform the shake estimating section, and comparing the estimationinformation with the second reference range when the estimationinformation is output, thereby determining on the basis of comparisonresults whether or not photography should be started.

According to a fifth aspect of the present invention, there is provideda camera with a blur reducing function, comprising:

a shake data sampling section, responsive to a releasing operation, forsampling, in a time series manner, a shake level in each of twodirections perpendicular to a photography optical axis of the camera andintersecting each other;

a “photography-with-moving-camera” determining section for determining,on the basis of an output of the shake data sampling section, whether ornot photography is being executed while moving the camera, andinvalidating data which is included in the output of the shake datasampling section and concerns a direction in which the camera is moving;and

a control section for starting photography when the output of the shakedata sampling section satisfies a predetermined reference value, or whena predetermined period has elapsed after the releasing operation.

According to a sixth aspect of the present invention, there is provideda camera for detecting levels of shaking in a plurality of directions inresponse to a releasing operation, and starting photography at a timepoint at which shaking is at a low level, comprising:

a shake level detecting, responsive to a releasing operation, fordetecting levels of shaking in a plurality of directions; and

a control section for determining, on the basis of levels of shaking inthe plurality of directions detected by the shake level detectingsection, whether or not photography is being executed while moving thecamera, the control section invalidating a shake state signal obtainedin a direction in which photography is being executed while moving thecamera.

According to a seventh aspect of the present invention, there isprovided a camera with a blur reducing function, comprising:

a time measuring section, responsive to a releasing operation, forstarting to measure a time period and stop it when a predetermined timelimit expires;

a shake detecting section for repeatedly detecting a shake level of thecamera; and

a photography start timing determining section for starting photography,when the predetermined time limit has expired or while time measurementis executed before the predetermined time limit expires, in accordancewith a comparison result between a predetermined reference range and anestimated level of shaking which is obtained, after a predeterminedperiod, on the basis of a plurality of shake data items including thedetected shake level and shake levels near the detected shake level,wherein

the photography start timing determining section increases thepredetermined period each time comparison has been executed.

According to a eighth aspect of the present invention, there is provideda camera with a blur reducing function, comprising:

a time measuring section, responsive to a releasing operation, forstarting to measure a time period and stop it when a predetermined timelimit expires;

a shake detecting section for repeatedly detecting a shake level of thecamera; and

a photography start timing determining section for starting photography,when the predetermined time limit has expired or while time measurementis executed before the predetermined time limit expires, in accordancewith a comparison result between a predetermined reference range and anestimated level of shaking which is obtained, after a predeterminedperiod, on the basis of a plurality of shake data items including thedetected shake level and shake levels near the detected shake level,wherein

the photography start timing determining section widens thepredetermined reference range each time comparison is executed.

According to a ninth aspect of the present invention, there is provideda method of reducing blurring in a photograph taken by a camera whichhas a sensor for detecting a shake state of the camera and can reduceshaking during exposure, comprising:

a first step of sampling levels of shaking in a time series manner onthe basis of an output of the sensor;

a second step of receiving a predetermined number of shake data itemssampled in the time series manner, thereby executing predeterminedcomputation of the shake data items;

a third step of comparing latest shake data, output from the sensor,with a first determination reference range;

a fourth step of comparing a computation result, when output at thesecond step, with a second determination reference range different fromthe first determination reference range; and

a fifth step of determining, on the basis of a comparison result at thethird step or the fourth step, whether or not exposure should bestarted.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention and, together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 is a block diagram illustrating the concept of a camera with ablur reducing function according to the invention;

FIG. 2 is a block diagram illustrating the concept of a camera with ablur reducing function according to a first embodiment of the invention;

FIG. 3 is a block diagram illustrating the structure of FIG. 2 in moredetail;

FIG. 4 is a block diagram illustrating the concept of a camera with ablur reducing function according to a second embodiment of theinvention;

FIG. 5 is a block diagram illustrating the structure of FIG. 4 in moredetail;

FIG. 6 is a block diagram illustrating the concept of a camera with ablur reducing function according to a third embodiment of the invention;

FIG. 7 is a block diagram illustrating the structure of FIG. 6 in moredetail;

FIG. 8 is a block diagram illustrating an essential part of asingle-lens reflex camera to which the camera with the blur reducingfunction according to each of the first to third embodiments of theinvention is applied;

FIG. 9 is a perspective view useful in explaining the mounting positionsof first and second shake sensors on a camera body;

FIG. 10 is a flowchart useful in explaining the operation of the cameraof FIG. 8;

FIG. 11 is a view showing a display example of information on a shakinglevel;

FIGS. 12A-12C are a series of flowcharts useful in explaining theexposure control operation in FIG. 10;

FIG. 13 is a timing chart useful in explaining a waiting period till thestart of shake detection;

FIG. 14A is a graph showing a shake detection result (a waveform)obtained by usual photography executed with a camera held by hand;

FIG. 14B is a graph showing a shake detection result (a waveform)obtained by photography executed with a slowly moving camera;

FIG. 14C is a graph showing a shake detection result (a waveform)obtained by photography executed with a quickly moving camera;

FIGS. 15A and 15B are a series of flowcharts useful in explaining the“photography-with-moving-camera” determination operation in FIG. 12B;

FIG. 16 is a flowchart useful in explaining an example of the exposurestart determination operation B in FIG. 12B;

FIG. 17 is a graph illustrating the relationship between the time andthe X- and Y-directional shake angular velocities, and useful inexplaining the exposure start determination operation B in FIG. 16;

FIG. 18 is a flowchart useful in explaining another example of theexposure start determination operation B in FIG. 12B;

FIG. 19 is a graph illustrating the relationship between the time andthe X- and Y-directional shake angular velocities, and useful inexplaining the exposure start determination operation B in FIG. 18;

FIG. 20 is a flowchart useful in explaining an example of the exposurestart determination operation A in FIG. 12B;

FIG. 21 is a graph illustrating the relationship between the time andthe X- and Y-directional shake angular velocities, and useful inexplaining the exposure start determination operation A in FIG. 20;

FIG. 22 is a flowchart useful in explaining another example of theexposure start determination operation A in FIG. 12B;

FIG. 23 is a graph illustrating the relationship between the time andthe X- and Y-directional shake angular velocities, and useful inexplaining the exposure start determination operation A in FIG. 22; and

FIG. 24 is a flowchart useful in explaining the post-exposure shakereport operation in FIG. 12C.

DETAILED DESCRIPTION OF THE INVENTION

Before describing the embodiments of the invention, the basic concept ofthe invention will be described.

FIG. 1 is a block diagram illustrating the concept of a camera with ablur reducing function according to the invention. The camera shown inFIG. 1 is a camera using a film.

A shake detecting/computing section 1 executes detection and computationof hand-shake levels. Actually, the shake detecting/computing section 1includes a pair of shake detecting/computing elements corresponding tothe X-axis and the Y-axis of a photography screen. An exposure startdetermining section 2 determines whether the present level of shaking ishigh or low, on the basis of the output (i.e. the level of hand-shake)of the shake detecting/computing section 1, thereby allowing the startof exposure when the level of shaking is low. A shutter unit 3 operatesand executes exposure in accordance with a determination result obtainedfrom the exposure start determining section 2. Anexposure-start-determining-method changing section 4 changes an exposurestart determination method employed in the exposure start determiningsection 2. A condition setting section 9 sets a changing condition,which is used in the exposure-start-determining-method changing section4, for changing the exposure start determination method employed in theexposure start determining section 2.

The operation of the camera with the blur reducing function constructedas above will be described briefly. Basically, the exposure startdetermining section 2 executes exposure start determination for reducingblurring on the basis of the output of the shake detecting/computingsection 1. At this time, the exposure start determination methodemployed in the exposure start determining section 2 is changed inaccordance with a changing condition set by the condition settingsection 9. Various types of changing conditions are considered and willbe specifically described with reference to the embodiments of theinvention.

The embodiments of the invention will now be described with reference todrawings.

FIG. 2 is a block diagram illustrating the concept of a camera with ablur reducing function according to a first embodiment of the invention.This embodiment employs a camera using a film as an example.

In the camera with the blur reducing function according to the firstembodiment, the condition setting section 9 is constituted of a cameracontrol section 6 for controlling all operations of the camera.

Specifically, in the camera with the blur reducing function according tothe first embodiment, the exposure start determining section 2 executesexposure start determination for blur reduction on the basis of theoutput of the shake detecting/computing section 1. At this time, inaccordance with the operation state of the camera, the exposure startdetermination method used in the exposure start determining section 2 ischanged. More specifically, preparatory operations (a mirror raisingoperation, a lens stop down operation, etc.) for exposure are executedin accordance with an exposure start instructing operation (a releasingoperation). After the completion of these preparatory operations, theshake detecting/computing section 1 and the exposure start determiningsection 2 are started to operate. The exposure-start-determining-methodchanging section 4 changes the exposure start determination method inthe exposure start determining section 2 before and after apredetermined period elapses from the start of each section.

FIG. 3 is a block diagram illustrating the structure of FIG. 2 in moredetail.

In FIG. 3, a shake estimating section 8 stores the output of the shakedetecting/computing section 1 and executes estimation of shaking on thebasis of the stored data. A shake-information-stored-state monitoringsection 45 monitors (checks) a shake information started state in theshake estimating section 8. The exposure-start-determining-methodchanging section 4 is incorporated in an exposure start determinationcontrolling section 5. An exposure start method setting section 21 isprovided between the exposure-start-determining-method changing section4 and the exposure start determining section 2.

The operation of the structure shown in FIG. 3 will be describedbriefly. Basically, the exposure start determining section 2 executesexposure start determination for reducing blurring on the basis of theoutput of the shake detecting/computing section 1. At this time, theshake-information-stored-state monitoring section 45 monitors (checks)the shake information stored state of the shake estimating section 8,and sends the monitoring result to the exposure-start-determining-methodchanging section 4. Upon receiving the monitoring result, theexposure-start-determining-method changing section 4 changes theexposure start determination method used in the exposure startdetermining section 2. Specifically, preparatory operations (a mirrorraising operation, a lens stop down operation, etc.) for exposure areexecuted in accordance with an exposure start instructing operation (areleasing operation). After the completion of these preparatoryoperations, the shake detecting/computing section 1, the shakeestimating section 8 and the exposure start determining section 2 arestarted to operate. At this time, the shake-information-stored-statemonitoring section 45 monitors whether or not a predetermined number(corresponding to a predetermined period) of shake levels areaccumulated in the shake estimating section 8, thereby changing theexposure start determination method in the exposure start determiningsection 2 before and after the predetermined number is reached. In otherwords, the exposure start determining section 2 executes exposure startdetermination on the basis of the output of the shakedetecting/computing section 1 until the predetermined number is reached,and executes the determination on the basis of the output of the shakeestimating section 8 after the predetermined number is reached.

The second embodiment of the invention will be described. FIG. 4 is ablock diagram illustrating the concept of a camera with a blur reducingfunction according to the second embodiment of the invention. Thisembodiment employs a camera using a film.

In the camera with the blur reducing function of the second embodiment,the condition setting section 9 is formed as a“photography-with-moving-camera” determining section 7 which determines,from the output of the shake detecting/computing section 1, i.e. from ashake level signal, whether or not photography is being executed whilemoving the camera.

In this type of camera, the exposure start determining section 2executes exposure start determination on the basis of the output of theshake detecting/computing section 1, and a reduction in the level ofshaking is waited for. In parallel with this operation, the“photography-with-moving-camera” determining section 7 determines, fromthe output of the shake detecting/computing section 1, whether or notphotography is being executed while moving the camera. If it isdetermined that photography is being executed while moving the camera,the determination method used in the exposure start determining section2 is changed. As a result, the exposure start determining section 2executes exposure start determination only on the basis of an outputobtained in a direction of shaking that is irrelevant to“photography-with-moving-camera”. This results in minimization of a timelag which is not necessary for “photography-with-moving-camera”, whilereducing blurring in a resultant photograph.

FIG. 5 is a block diagram illustrating the structure of FIG. 4 in moredetail.

Specifically, the exposure-start-determining-method changing section 4is incorporated in the exposure start determination controlling section5. The exposure start determination controlling section 5 also includesa time lag measuring section 24 and a time lag limit setting section 25.

The operation of the structure shown in FIG. 5 will be describedbriefly. When the “photography-with-moving-camera” determining section 7has determined that photography is being executed while moving thecamera, it is considered that the shutter operation can be more easilyallowed than in the case of usual photography, and hence a period forexposure determination control in the exposure start determining section2 is set short so as to shorten the time lag as much as possible.Specifically, a short period is set in the time lag limit settingsection 25, and the set period is compared with a period which is beingmeasured by the time lag measuring section 24. If the measured periodreaches the set period, the exposure start determination executed by theexposure start determining section 2 is finished, and an exposureoperation is executed by the shutter unit 3.

A third embodiment of the invention will be described. FIG. 6 is a blockdiagram illustrating the concept of a camera with a blur reducingfunction according to the third embodiment of the invention. Thisembodiment employs a camera using a film as an example.

In the camera with the blur reducing function according to the thirdembodiment, the condition setting section 9 is constituted of the timelag measuring section 24 for measuring a period (a time lag) which haselapsed after exposure start determination is executed by the exposurestart determining section 2 for starting the operation of the shutterunit 3.

In this type of camera, the exposure start determining section 2executes exposure start determination on the basis of the output of theshake detecting/computing section 1, and a reduction in the level ofshaking is waited for. The exposure-start-determining-method changingsection 4 determines the wait period, i.e. the time lag, and changes thedetermination method used in the exposure start determining section 2.As a result, the resultant time lag is shortened, while shake reductionis executed.

FIG. 7 is a block diagram illustrating the structure of FIG. 6 in moredetail.

The exposure-start-determining-method changing section 4 is incorporatedin the exposure start determination controlling section 5. The exposurestart determination controlling section 5 also includes an exposurestart determination period setting section 22, an exposure startdetermination level setting section 23, the time lag measuring section24, the time lag limit setting section 25, and a time lag informationstorage 26.

The operation of the structure shown in FIG. 7 will be describedbriefly. The exposure-start-determining-method changing section 4compares time information stored in the time lag information storage 26with the measurement result of the time lag measuring section 24.Further, the exposure-start-determining-method changing section 4changes the exposure start determination method used in the exposurestart determining section 2, in accordance with the lapse of time. Morespecifically, the changing section 4 changes shake allowable periodinformation, which is set in the exposure start determination periodsetting section 22 and concerns the shake level output from the shakedetecting/computing section 1, and determination level information,which is set in the exposure start determination level setting section23 and concerns the shake level output from the shakedetecting/computing section 1. This structure can provide an advantageas described above with reference to FIG. 6.

FIG. 8 is a block diagram illustrating an essential part of asingle-lens reflex camera to which the camera with the blur reducingfunction according to each of the first to third embodiments of theinvention is applied.

The shake detecting/computing section 1 includes a first shake sensor11, a second shake sensor 12, a first shake information sampling section13, a second shake information sampling section 14, a first shakecomputing section 15 and a second shake computing section 16. The words“first” and “second” correspond to the X-axis and the Y-axis,respectively.

The first and second shake sensors 11 and 12 are formed of, for example,a known oscillation gyroscope (an angular velocity sensor). The firstand second shake information sampling sections 13 and 14 are formed ofan A/D conversion input port incorporated in a CPU. Further, eachelement located downstream of the first and second shake informationsampling sections 13 and 14, which will be described later, is realizedby the CPU, except for a storage formed of, for example, an EEPROM.

The first and second shake computing sections 15 and 16 execute, forexample, a filtering operation on sampled data concerning shaking foreliminating any unnecessary frequency component. The outputs of the twoshake computing sections 15 and 16 are sent to the exposure startdetermining section 2, a “photography-with-moving-camera” determiningsection 7 for determining whether or not photography is being executedwhile moving the camera, a shake estimating section 8 and a shake statedetermining section 51.

The first and second shake sensors 11 and 12 are provided in a camerabody 81 as shown in FIG. 9. In FIG. 9, reference numeral 74 denotes arelease button, and reference numeral 82 denotes a lens.

The “photography-with-moving-camera” determining section 7 determineswhether or not photography is being executed while moving the camera, onthe basis of the output of the shake detecting/computing section 1, andincludes a first “photography-with-moving-camera” state determiningsection 31 and a second “photography-with-moving-camera” statedetermining section 32. The words “first” and “second” correspond to theX-axis and the Y-axis, respectively. The determination results of thesections 31 and 32 are sent to an exposure-start-determining-methodchanging section 4.

The shake estimating section 8 estimates the state of shaking on thebasis of the output of the shake detecting/computing section 1. Thesection 8 includes a first shake information storage 41, a second shakeinformation storage 42, a first shake estimating/computing section 43and a second shake estimating/computing section 44. The words “first”and “second” correspond to the X-axis and the Y-axis, respectively. Thefirst and second shake information storages 41 and 42 store past dataconcerning the state of shaking, which is used for operations in thefirst and second shake estimating/computing sections 43 and 44. Thefirst and second shake estimating/computing sections 43 and 44 estimatethe levels of shaking at a time point slightly after the present timepoint by operations based on present/past shake level data stored in thefirst and second shake information storages 41 and 42, respectively.Specifically, the shake estimating operation is executed by a method asdisclosed in Japanese Patent Application KOKAI Publication No. 5-204012.This method will be described briefly. The following formula is used forthe estimating operation:

BL(t+m)=Ka*BL(t)+Kb*BL(t−10)+Kc*BL(t−20)

where BL(t+m) represents the level of shaking at a time point m[mSEC]after the present time point, BL(t) the level of shaking at the presenttime point, BL(t−10) the level of shaking at a time point 10[mSEC]before the present time point, and BL(t−20) the level of shaking at atime point 20[mSEC] before the present time point. Ka, Kb and Kcrepresent coefficients for the estimating operation. From thisoperation, the level of shaking slightly after the present time pointcan be estimated on the basis of shake information concerning thepresent time point and the two earlier time points. The formula and thecoefficients are common between the X-axis and the Y-axis.

The thus-obtained estimation results are sent to the exposure startdetermining section 2. A shake-information-stored-state monitoringsection 45 checks whether the first and second shake informationstorages 41 and 42 each store a predetermined number (corresponding to apredetermined period) of shake level data items. The checking resultsare sent to the exposure-start-determining-method changing section 4,where the results are used as a basis for changing the exposure startdetermining method employed in the exposure start determining section 2.

The shake state determining section 51 calculates the present level ofblurring in an image on the basis of shake level data from the shakedetecting/computing section 1, focal distance information from a focaldistance information detecting section 52, and exposure periodinformation from an exposure period information detecting section 53.The calculation result is sent to the camera control section 6, and astate reporting section 66 incorporated in an intra-viewfinder displaysection 67 informs (displays) the present level of shaking.

The camera control section 6 controls the entire camera. FIG. 8 showsonly elements relating to the present invention and none of the otherelements.

The outputs of an exposure stand-by instructing section 54 (a firstrelease) and an exposure start instructing section 55 (a second release)are input to the camera control section 6. When the two-stage releasebutton 74 has been half depressed, the exposure stand-by instructingsection 54 generates a first release signal. Upon receiving the firstrelease signal, the camera control section 6 executes known photographypreparation operations such as AE and AF operations, a lens protrudingoperation, etc. Simultaneously, the camera control section 6 supplies aninstruction to the shake detecting/controlling section 56 to drive theshake detecting/computing section 1 in order to inform the level ofgenerated shaking.

When the release button 74 has been wholly depressed, the exposure startinstructing section 55 generates a second release signal. Upon receivingthe second release signal, the camera control section 6 executes anoperation for exposure. Specifically, in the case of a single-lensreflex camera, the mirror driving section 61 drives the quick returnmirror 62 so that light guided thereto from the lens 82 can reach animaging surface (film). The operation state monitoring section 63 ismeans for monitoring the operation state of the quick return mirror 62.In addition, a lens stop (not shown) is driven to a required stop value.When the mirror 62 and the lens stop have been shifted to respectivepredetermined states, a shutter driving section 64 drives the shutterunit 3. After a predetermined exposure period passes, exposure isfinished, whereby the mirror 26 and the lens stop are returned topredetermined positions, and the film is wound. This is the terminationof a series of exposure operations.

In the camera of this embodiment, the blur reducing function is executedat this time. Specifically, detection of shaking is started when themirror has stopped its operation, thereby monitoring the level ofshaking. If it is determined, using a predetermined algorithm, that thelevel of shaking has reduced, the shutter unit 3 is allowed to operate.The above-described series of operations will be referred to as“exposure start timing control”. When the raising operation of themirror 62 is completed, the camera shakes. If, at this time, the shakedetection result is used without any correction, it is possible that theaforementioned shake estimating operation result will be adverselyaffected. This leads to reduction of the blur reducing effect. To avoidit, it is necessary to consider the timing for starting the shakedetecting operation. The operation period information storage 65 storesinformation concerning this timing. The period information may consistof fixed values, and may be stored in a memory such as an EEPROM.

The above-mentioned exposure start timing control is executed by theexposure start determining section 2 and an exposure start determinationcontrolling section 5. The exposure start determination controllingsection 5 includes the exposure-start-determining-method changingsection 4, as well as an exposure start determination method settingsection 21, an exposure start determination period setting section 22and an exposure start determination level setting section 23. Theexposure start determining section 2 executes an exposure startdetermination basically on the basis of parameters set in these settingsections 21, 22 and 23.

Specifically, an algorithm (which will be described later in detail) forexposure start determination is set in the exposure start determinationmethod setting section 21. Information concerning exposure startdetermination periods for the X-axis and the Y-axis included in theparameters for the exposure start determination is stored in theexposure start determination period setting section 22. If thedetermination period is set long, the frequency of generation of anexposure start allowing signal is high, whereas if the period is setshort, the frequency is low. Information concerning a determinationlevel (threshold) for determining the level of shaking, which isincluded in the parameters for the exposure start determination, is setin the exposure start determination level setting section 23. If thedetermination level is set high, the frequency of generation of theexposure start allowing signal is high, whereas if the level is set low,the frequency is low. These information items are set at requiredvalues.

In the exposure start timing control, it is basically considered thatexposure is started when the level of shaking has become low. In thiscase, however, exposure cannot be started unless the shaking levelbecomes low. Accordingly, there may be a case where exposure can neverbe started, and the photographer misunderstands that the camera iserroneously operating. To avoid this, the exposure start timing controlis generally stopped, irrespective of the shaking level, after apredetermined period elapses. Moreover, it is considered to execute theexposure start timing control so as to output the exposure startallowing signal before the above-described predetermined period has beenreached, i.e. so as to shorten a delay period (a release time lag).Specifically, the parameter set in the exposure start determinationperiod setting section 22 or the exposure start determination levelsetting section 23, and used in the exposure start determining section2, is changed in accordance with a period having elapsed from the startof the exposure start timing control. Furthermore, the photographer canbe warned by being informed, through the state reporting section 66 ofthe intra-viewfinder display section 67, of the fact that the exposuretiming control is being executed for more than a predetermined period(this means that the level of shaking is not low).

To execute the above operations, the exposure start determinationcontrolling section 5 also contains a time lag measuring section 24, atime lag limit setting section 25 and a time lag information storage 26.The time lag measuring section 24 measures a period for which theexposure start timing control is executed, i.e. a time lag which hasoccurred. The time lag limit setting section 25 sets information on apredetermined time at which the exposure start timing control should befinished. The time lag information storage 26 stores a predeterminedperiod shorter than a time lag limit, which is used as a basis forchanging information set in, for example, the exposure startdetermination period setting section 22 in accordance with the exposurestart timing control period, or a basis for the informing operation ofthe state reporting section 66. The time lag measuring section 24, thetime lag limit setting section 25 and the time lag information storage26 are connected to the exposure-start-determining-method changingsection 4. In the section 4, determination concerning time is executed.

FIG. 10 is a flowchart useful in explaining the camera constructed asabove.

When a battery has been mounted in the camera or the power switch (notshown) of the camera has been turned on, and the camera has statedoperating, the camera is first initialized (step S1), and is thenshifted to a state in which it waits for the turn-on of a first releasesignal (1R) by the exposure stand-by instructing section 54 (step S2).

When the 1R has been turned on, the exposure period informationdetecting section 53 executes photometry (AE) (step S3) and the focaldistance information detecting section 52 executes ranging (AF) (stepS4). In accordance with focal distance information obtained by the AF,the lens 82 is driven (lens drive (LD))(step S5). It is determined at astep S6 whether the LD operation is executed appropriately (i.e. the LDoperation is OK). If the LD operation is not OK, turn-off of the 1R iswaited for (step S11), thereby returning to the step S2.

On the other hand, if the LD operation is determined to be OK, the shakedetecting/computing section 1 executes detection and computation ofshaking (step S7). Upon receiving the detecting/computing result, theshake state determining section 51 calculates the level of shaking,whereby the state reporting section 66 reports the calculated shakelevel (step S8).

Referring then to FIG. 11, a display example of the shaking level willbe described. AS shown, the intra-viewfinder display section 67 isprovided below a viewfinder field frame 75 equipped with a guide 76 forindicating a ranging point. The intra-viewfinder display section 67includes, as well as the state reporting section 66, a photographyinformation display section 77 for displaying an exposure period, a stopvalue, etc., and a blur reducing mode display section 78 for displayingwhether or not a blur reducing mode is set by blur reducing mode settingmeans (not shown). Means that can display the level of shaking in threestages may be used as the state reporting section 66. In this case, alighting display denoted by (a) indicates shaking of a low level, alighting display denoted by (b) indicates shaking of an intermediatelevel, and a lighting display denoted by (c) indicates shaking of a highlevel.

After informing the state of shaking as above, it is determined at astep S9 whether or not the exposure start instructing section 55 hasturned on a second release signal (2R). If the 2R is in the OFF state,it is determined at a step S12 whether or not the 1R is in the OFFstate. If the IR is determined to be in the ON state, the programreturns to the step S7, thereby repeating the shake detecting/computingprocessing and the shake informing processing. If, on the other hand,the 1R is determined to be in the OFF state, the program returns to thestep S2.

If the 2R is turned on, exposure control operation as described later isperformed (step S10). After finishing the exposure control operation,the program returns to the step S2.

The “exposure control” operation at the step S10 is specifically carriedout as indicated by a series of flowcharts of FIGS. 12A-12C.

First, the shake detecting/computing processing by the shakedetecting/computing section 1 and the shaking-state informing processingby the state reporting section 66 are stopped simultaneously (stepS101). Then, the quick return mirror 62 is raised by the mirror drivingsection 61 (step S102), and a lens stop mechanism (not shown) is drivento stop down the lens (step S103).

Subsequently, it is determined whether or not the state of themirror-raising switch has changed (step S104). This determination ismade on the basis of information output from the operation statemonitoring section 63, and repeated until the state of the switchchanges.

If there is a change in the state of the mirror-raising switch, timinginformation for starting the shake detecting processing is read from theoperation period information storage 65 (step S105).

After that, RAM (counters) and flags (concerning the meanings of eachcounter and flag, see FIG. 12A), which are used in relation to exposuretiming control described below, are cleared (initialized) (step S106).

It is determined at a step S107 whether or not a period equal to theperiod read at the step S105 has elapsed. This determination is repeateduntil the period elapses.

Referring then to the flowchart of FIG. 13, a description will be givenof the above-mentioned waiting period. In FIG. 13, the top waveformindicates the state of shaking (changes in position) due to a mirrorraising operation, the next waveform down indicates the state of themirror-raising switch (corresponding to the output signal of theoperation state monitoring section 63), the next waveform down indicatesa time point at which the RAM and flags relating to the exposure timingcontrol are cleared (at the step S106), and the bottom waveformindicates the ON/OFF states of the shake detecting operation (samplingoperation). The abscissa indicates the time axis.

The period required until vibration caused by the mirror-raisingoperation actually stops is as long as several hundreds of milliseconds.If, however, shake detection (sampling) is started after the periodelapses, a very long time lag occurs. To avoid this, shake detection isstarted after a period after which it is considered that no problemoccurs in shake detecting processing, even when vibration has beengenerated because of the mirror-raising operation. This period isshorter than the period required until vibration caused by themirror-raising operation actually ceases, and is stored in the operationperiod information storage 65.

If it is determined at the step S107 that the detection start time hasbeen reached, a shake detection cycle timer is started (step S111). Thisenables sampling of shake information at regular cycles.

After that, shake information sampling corresponding to the X-axis of animaging surface is executed by a first shake information samplingsection 13 (step S112), while shake information sampling correspondingto the Y-axis of the imaging surface is executed by a second shakeinformation sampling section 14 (step S113). Then, shake computingprocessing corresponding to the X-axis of an imaging surface is executedby a first shake computing section 15 (step S114), while shake computingprocessing corresponding to the Y-axis of the imaging surface isexecuted by a second shake computing section 16 (step S115). On thebasis of shake information obtained by the shake computing sections 15and 16, determination as to whether or not photography is being executedwhile moving the camera is executed by the“photography-with-moving-camera” determining section 7 (step S116). Themethod for “photography-with-moving-camera” determination will bedescribed later.

Subsequently, the shake information corresponding to the X-axis of theimaging surface and obtained by the first shake computing section 15 isstored in a first shake information storage 41 (step S117). Similarly,the shake information corresponding to the Y-axis of the imaging surfaceand obtained by the second shake computing section 16 is stored in asecond shake information storage 42 (step S118). Thereafter, the valueof a counter B_COUNTA for counting the number of data items accumulatedfor shake estimation and computation (this counter constitutes ashake-information-stored-state monitoring section 45) is incremented(step S119). It is determined at the next step S120 whether or not theresultant value of the counter B_COUNTA is not less than a predeterminedvalue. This enables determination as to whether or not each of the firstand second shake information storages 41 and 42 stores not less than apredetermined number (i.e. not less than a predetermined period) ofshake information items. If it is determined that the value of thecounter is not less than the predetermined value, the program proceedsto a step S122, whereas if the value is less than the predeterminedvalue, the program proceeds to a step S121.

This means that unless the predetermined number of shake informationitems are stored, exposure start determination cannot be executed usingthe shake estimation method. Therefore, if it is determined that thepredetermined number of shake information items are not yet stored, theexposure start determining section 2 executes an exposure startdetermination operation A using the present shake information (stepS121). The exposure start determination operation A will be describedlater in detail. If it is determined as a result of the exposure startdetermination operation A that exposure should be executed, aleading-curtain-drive-start start allowing flag F_GOFLAG is set at “1”.

On the other hand, if the predetermined number (corresponding to thepredetermined period) or more of shake information items are stored,exposure start determination using the shake estimation method ispossible. In this case, shake estimation/computation corresponding tothe X-axis of the imaging surface is executed by the first shakeestimating/computing section 43 (step S122), and shakeestimation/computation corresponding to the Y-axis of the imagingsurface is executed by the second shake estimating/computing section 44(step S123). After that, the exposure start determining section 2executes an exposure start determination operation B using the shakeestimation/computation results (step S124). The exposure startdetermination operation B will be described later in detail. If, also inthe determination operation B, it is determined that exposure should beexecuted, the leading-curtain-drive-start start allowing flag F_GOFLAGis set at “1”.

After the execution of the exposure start determination operations A andB, it is determined whether or not the leading-curtain-drive-start startallowing flag F_GOFLAG is set at “1” (step S125). If it is determinedthat the leading-curtain-drive-start start allowing flag F_GOFLAG is not“1”, the value of a time lag counter B_COUNTB is incremented (stepS126). Supposing that the cycle of processing from the step S111 to astep S136 described later is constant, this is equivalent to a casewhere time measurement is executed by the time lag measuring section 24.

After that, it is determined whether or not the value of the time lagcounter B_COUNTB is not less than “150” (step S127). This meansdetermination as to whether or not 300 milliseconds have elapsed fromthe start of the exposure start timing control, if the cycle ofprocessing from the step S111 to the step S136 is, for example, 2milliseconds. In this case, information concerning the time period isset in the time lag limit setting section 25.

If it is determined whether or not the value of the time lag counterB_COUNTB does not yet reach “150”, it is further determined whether ornot the value of the time lag counter B_COUNTB is not less than “51”(step S128). This means determination as to whether or not 100milliseconds have elapsed from the start of the exposure start timingcontrol, if the cycle of processing from the step S111 to the step S136is, for example, 2 milliseconds. In this case, information concerningthe time period is stored in the time lag information storage 26. If thestored period is not reached, i.e., if it is determined that the valueof the time lag counter B_COUNTB does not yet reach “51”, waitingprocessing is executed at a step S129 until a predetermined time periodis measured by the shake detection cycle timer that is made to start atime measurement at the step S111. After the predetermined periodelapses, the program returns to the step S111, thereby repeating theabove-described sequential processing. The timer predetermined period isset at, for example, 2 milliseconds.

After the loop from the step S111 to the step S129 is repeated fiftytimes, it is determined in the 51st loop that the value of the time lagcounter B_COUNTB is not less than “15”. In this case, it is furtherdetermined at a step S130 whether or not the value of the time lagcounter B_COUNTB is not less than “100”. This means determination as towhether or not 200 milliseconds have elapsed from the start of theexposure start timing control, if the cycle of processing from the stepS111 to the step S136 is, for example, 2 milliseconds. In this case,information concerning the time period is stored in the time laginformation storage 26.

If it is determined that the elapsed period is less than 200milliseconds, the program proceeds to a step S131, while if the elapsedperiod is not less than 200 milliseconds, the program proceeds to a stepS134. Thus, if the period elapsed after the start of the exposure starttiming control is between 102 milliseconds and 200 milliseconds,processes at steps S131-S133 are executed. On the other hand, if theperiod elapsed after the start of the exposure start timing control isnot less than 200 milliseconds, processes at steps S134-S136 areexecuted.

Specifically, if it is determined that the value of the time lag counterB_COUNTB is not more than “100”, at first, first time lag stateinforming is executed using the state reporting section 66 in theintra-viewfinder display section 67 (step S131). At this time, it isreported that 102 milliseconds or more have elapsed after the start ofthe exposure start timing control. For example, a single lightingdisplay as indicated by (a) of FIG. 11 may be executed.

Subsequently, it is determined at a step S132 whether or not the valueof the time lag counter B_COUNTB is “51”. If the answer to the questionat the step S132 is Yes, the program proceeds to a step S133, whereas ifthe answer is No, the program proceeds to the step S129. In other words,if the value of the time lag counter B_COUNTB is “51”, the exposurestart determining period is changed or the exposure start determininglevel is changed (step S133). More specifically, the determining periodinformation set in the exposure start determination period settingsection 22 is changed to a higher value, or the shake statedetermination level (threshold value) set in the exposure startdetermination level setting section 23 is changed to a higher value.This processing is executed on the assumption that even while the levelof shaking is reduced by the exposure start timing control, the start ofexposure can be easily allowed, thereby minimizing a possible time lag.After this changing processing, the program proceeds to the step S129.

After the above loop is repeated fifty times more, i.e. if the loop isthe 101st one when it is counted from the beginning, it is determined atthe step S130 that the value of the time lag counter B_COUNTB is notless than “100”. In this case, second time lag informing is executedusing the state reporting section 66 of the intra-viewfinder displaysection 67 (step S134). Specifically, the fact that 200 milliseconds ormore have passed after the start of the exposure start timing control isreported. To inform this fact, it is considered to use two lightingdisplays as denoted by (b) of FIG. 11. The second time lag informationindicates a stronger warning than the first time lag information issuedat the step S131.

Subsequently, it is determined whether or not the value of the time lagcounter B_COUNTB is “101” (step S135). If the answer is Yes, the programproceeds to a step S136, whereas if the answer is No, the programproceeds to the step S129. If the value of the time lag counter B_COUNTBis “101”, the exposure start determining period is again changed or theexposure start determining level is again changed (step S136). Morespecifically, the determining period information set in the exposurestart determination period setting section 22 is changed to a highervalue (which is higher than the value set at the step S133), or theshake state determination level (threshold value) set in the exposurestart determination level setting section 23 is changed to a highervalue (which is higher than the value set at the step S133). Thisprocessing is executed on the assumption that even while the level ofshaking is reduced by the exposure start timing control, the start ofexposure can be allowed more easily than at the step S133, therebyfurther minimizing a possible time lag.

If it is determined at the step S125 that theleading-curtain-drive-start start allowing flag F_GOFLAG is “1”, beforethe above loop is repeated 150 times, exposure is started. Accordingly,the information of the shaking level through the state reporting section66 in the intra-viewfinder display section 67 at the step S131 or S134is turned off (step S137).

On the other hand, if the leading-curtain-drive-start start allowingflag F_GOFLAG is not “1” even after the loop is repeated 150 times, itis determined that the exposure timing control should be finished, whenit has been determined at the step S127 that the value of the time lagcounter B_COUNTB has reached “150” or more, i.e. when the time lag limithas expired. In this case, a time lag limit over flag F_OVER is set at“1” (step S138), and then the program proceeds to the step S137.

After the shaking state information is stopped at the step S137, theleading-curtain-driving operation of the shutter unit 3 is started (stepS139). In other words, exposure is started. At the next step S140, it isdetermined whether or not the period of exposure has reached apredetermined value detected by the exposure period informationdetecting section 53.

If it is determined that the predetermined exposure period is not yetreached, processing for detecting the level of shaking during exposureand informing it after exposure is executed. Specifically, at first, itis determined at a step S141 whether or not the shake detection cycletimer having started its operation at the step S111 has counted apredetermined period. If it is determined that the predetermined periodhas elapsed, the first shake information sampling section 13 executesshake information sampling in the direction of the imaging surfaceX-axis (step S142), and the second shake information sampling section 14executes shake information sampling in the direction of the imagingsurface Y-axis (step S143). Then, the first shake computing section 15executes computation processing of X-axis directional shaking (stepS144), while the second shake computing section 16 executes computationprocessing of Y-axis directional shaking (step S145). After that, theshake state determining section 51 calculates the level of blurring inan image on the basis of shake information obtained from the first andsecond shake computing sections 15 and 16 (step S146). Then, the programreturns to the step S140. The level of blurring is obtained by, forexample, integrating shake information items obtained during exposurefrom the first and second shake computing sections 15 and 16.

If it is determined at the step S140 that the predetermined exposureperiod has elapsed, the trailing-curtain-driving operation of theshutter unit 3 is started at a step S147. In other words, exposure isfinished. At the next step S148, the mirror driving section 61 lowersthe quick return mirror 62. Then, at a step S149, the lens stopmechanism (not shown) is released, and at a step S150, a film windingoperation is executed by a film driving mechanism (not shown). It isdetermined at a step S151 whether or not a series of processing from thestep S148 to the step S150 has been finished. If it is determined thatthe processing has been finished, post-exposure reporting of the stateof shaking during exposure and the state of exposure start timingcontrol (as to whether or not exposure is started, irrespective of thestate of shaking, after the time lag limit has expired) is executed at astep S152. A detailed description will be given later of a method forpost-exposure shake report operation. After that, the “exposure control”operation is finished, and the program returns to the main routine(RETURN).

Although “150”, “51”, “100”, and “101” are set at the steps S127, S128and S132, S130, and S135, the invention is not limited to these values(periods), but any other appropriate values may be set at the steps. Itsuffices if a common basic idea is employed between the cases.

A method for “photography-with-moving-camera” determination operationwill now be described.

FIGS. 14A-14C show different shake detection results (waveforms)obtained from usual photography with a camera held by hand and obtainedfrom photography with a moving camera. In FIGS. 14A-14C, the ordinateindicates the voltage [V] corresponding to the angular velocity[DEG/SEC] of shaking, Vref corresponding to a shake angular velocity of±0. Further, the abscissa indicates time. More specifically, FIG. 14Ashows an example of a waveform obtained from usual photography with acamera held by hand. FIGS. 14B and 14C show examples of waveformsobtained from photography with a moving camera.

As is understood from FIG. 14A, the shake angular velocity often crosses±0 in the case of usual photography with a camera held by hand. On theother hand, in the case of photography with a moving camera, the shakeangular velocity does not so often cross or never crosses ±0 as shown inFIGS. 14B and 14C, since the camera is being moved in a certaindirection. FIG. 14B shows a waveform obtained when the camera is slowlymoved, while FIG. 14C shows a waveform obtained when the camera is movedat a highest speed allowable in an analog processing system for shakedetection.

FIGS. 15A and 15B are a series of flowcharts useful in explaining amethod employed at the step S116 for “photography-with-moving-camera”determination operation.

First, it is determined whether or not the present X-axis directionalshake level (the output of the first shake computing section 15) has a“+” sign (step S201). In other words, it is determined whether or notthe shake level is higher than the voltage Vref shown in FIGS. 14A-14C.If the level has the “+” sign, the program proceeds to the next stepS202, whereas if the level does not have the “+” sign, the programproceeds to a step S209.

If the present X-axis directional shake level has the “+” sign, a shakelevel (X) sign flag F_XDIRN indicating the sign of the present shakelevel (X) is set at “1” (step S202). At the next step S203, it isdetermined whether or not a shake level (X) sign flag F_XDIRO indicatingthe sign of a shake level (X) previously sampled is set at “1”(corresponding to the “+” sign). If the shake level (X) sign flagF_XDIRO is “1”, the program proceeds to the next step S204 since thepresent shake level and the previous shake level both have the “+” sign.On the other hand, if the shake level (X) sign flag F_XDIRO is not “1”,the program proceeds to a step S207 which will be described later, sincethis means that the shake angular velocity has crossed ±0.

More specifically, if the shake level (X) sign flag F_XDIRO is “1”, thevalue of a counter B_XDIRP for counting the number of shake levels (X)that exist in a “+” zone is incremented (step S204), thereby determiningwhether or not the incremented value of the counter B_XDIRP is not lessthan a predetermined value (step S205). If the value of the counterB_XDIRP is not equal to or not more than the predetermined value, theprogram immediately proceeds to a step S216 which will be describedlater. If, on the other hand, the value is not less than thepredetermined value, it is determined that photography is being executedwhile moving the camera in the X-axis direction of the imaging surface,thereby setting, at “1”, a flag F_XBL indicating photography executedwhile moving the camera in the X-axis direction (step S206), followed bythe program proceeding to the step S216.

If it is determined at the step S203 that the shake level (X) sign flagF_XDIRO is not “1”, i.e. if the shake angular velocity has crossed ±0,the counter B_XDIRP and a counter B_XDIRM for counting the number ofshake levels (X) that exist in a “−” zone are cleared (step S207). Afterthat, the flag F_XBL is set at “0” (step S208), and the program proceedsto the step S216.

On the other hand, if it is determined at the step S201 that the presentX-axis directional shake level does not have the “+” sign, the shakelevel (X) sign flag F_XDIRN indicating the sign of the present shakelevel (X) is set at “0” (step S209). Then, it is determined whether ornot the shake level (X) sign flag F_XDIRO indicating the sign of a shakelevel (X) previously sampled is “0” (corresponding to the “−” sign)(stepS210). If the flag F_XDIRO is “0”, the program proceeds to the next stepS211, since the result means that the present shake level and theprevious shake level have the same sign. If the flag is not “0”, theprogram proceeds to a step S214 which will be described later, since theresult means that the shake angular velocity has crossed ±0.

More specifically, if the shake level (X) sign flag F_XDIRO is “0”, thevalue of the counter B_XDIRM for counting the number of shake levels (X)that exist in the “−” zone is incremented (step S211), therebydetermining whether or not the incremented value of the counter B_XDIRMis not less than a predetermined value (step S212). If the value of thecounter B_XDIRM is not equal to or not more than the predeterminedvalue, the program immediately proceeds to a step S216 which will bedescribed later. If, on the other hand, the value is not less than thepredetermined value, it is determined that photography is being executedwhile moving the camera in the X-axis direction of the imaging surface,thereby setting, at “1”, the flag F_XBL indicating photography executedwhile moving the camera in the X-axis direction (step S213), followed bythe program proceeding to the step S216.

If it is determined at the step S210 that the shake level (X) sign flagF_XDIRO is not “0”, i.e. if the shake angular velocity has crossed ±0,the counter B_XDIRP and the counter B_XDIRM are cleared (step S214).After that, the flag F_XBL is set at “0” (step S215), and the programproceeds to the step S216.

The processes at the steps S201-S215 are executed in the first“photography-with-moving-camera” state determining section 31incorporated in the “photography-with-moving-camera” determining section7.

The same processing as above will be executed in the Y-axis direction ofthe imaging surface.

First, it is determined whether or not the present Y-axis directionalshake level (the output of the second shake computing section 16) has a“+” sign (step S216). In other words, it is determined whether or notthe shake level is higher than the voltage Vref shown in FIGS. 14A-14C.If the level has the “+” sign, the program proceeds to the next stepS217, whereas if the level does not have the “+” sign, the programproceeds to a step S224.

If the present Y-axis directional shake level has the “+” sign, a shakelevel (Y) sign flag F_YDIRN indicating the sign of the present shakelevel (Y) is set at “1” (step S217). At the next step S218, it isdetermined whether or not a shake level (Y) sign flag F_YDIRO indicatingthe sign of a shake level (Y) previously sampled is set at “1”(corresponding to the “+” sign). If the shake level (Y) sign flagF_XYIRO is “1”, the program proceeds to the next step S219 since thepresent shake level and the previous shake level both have the “+” sign.On the other hand, if the shake level (Y) sign flag F_YDIRO is not “1”,the program proceeds to a step S222 which will be described later, sincethis means that the shake angular velocity has crossed ±0.

More specifically, if the shake level (Y) sign flag F_YDIRO is “1”, thevalue of a counter B_YDIRP for counting the number of shake levels (Y)that exist in the “+” zone is incremented (step S219), therebydetermining whether or not the incremented value of the counter B_YDIRPis not less than a predetermined value (step S220). If the value of thecounter B_YDIRP is not equal to or not more than the predeterminedvalue, the program immediately proceeds to a step S231 which will bedescribed later. If, on the other hand, the value is not less than thepredetermined value, it is determined that photography is being executedwhile moving the camera in the Y-axis direction of the imaging surface,thereby setting, at “1”, a flag F_YBL indicating photography executedwhile moving the camera in the Y-axis direction (step S221), followed bythe program proceeding to the step S231 described later.

If it is determined at the step S218 that the shake level (Y) sign flagF_YDIRO is not “1”, i.e. if the shake angular velocity has crossed ±0,the counter B_YDIRP and a counter B_YDIRM for counting the number ofshake levels (Y) that exist in a “−” zone are cleared (step S222). Afterthat, the flag F_YBL is set at “0” (step S223), and the program proceedsto the step S231 described later.

On the other hand, if it is determined at the step S216 that the presentY-axis directional shake level does not have the “+” sign, the shakelevel (Y) sign flag F_YDIRN indicating the sign of the present shakelevel (Y) is set at “0” (step S224). Then, it is determined whether ornot the shake level (Y) sign flag F_YDIRO indicating the sign of a shakelevel (Y) previously sampled is “0” (corresponding to the “−” sign)(stepS225). If the flag F_YDIRO is “0”, the program proceeds to the next stepS226, since the result means that the present shake level and theprevious shake level have the same sign. If the flag is not “0”, theprogram proceeds to a step S229 which will be described later, since theresult means that the shake angular velocity has crossed ±0.

More specifically, if the shake level (Y) sign flag F_YDIRO is “0”, thevalue of the counter B_YDIRM for counting the number of shake levels (Y)that exist in the “−” zone is incremented (step S226), therebydetermining whether or not the incremented value of the counter B_YDIRMis not less than a predetermined value (step S227). If the value of thecounter B_YDIRM is not equal to or not more than the predeterminedvalue, the program immediately proceeds to the step S231 describedlater. If, on the other hand, the value is not less than thepredetermined value, it is determined that photography is being executedwhile moving the camera in the Y-axis direction of the imaging surface,thereby setting, at “1”, the flag F_YBL indicating photography executedwhile moving the camera in the Y-axis direction (step S228), followed bythe program proceeding to the step S231.

If it is determined at the step S225 that the shake level (Y) sign flagF_YDIRO is not “0”, i.e. if the shake angular velocity has crossed ±0,the counter B_YDIRP and the counter B_YDIRM are cleared (step S229).After that, the flag F_YBL is set at “0” (step S230), and the programproceeds to the step S231 described later.

The processes at the steps S216-S230 are executed in the second“photography-with-moving-camera” state determining section 32incorporated in the “photography-with-moving-camera” determining section7.

After the X-axis directional and Y-axis directional processing isfinished, the value of the shake level (X) sign flag F_XDIRN indicatingthe sign of the present shake level (X) is written into the shake level(X) sign flag F_XDIRO indicating the sign of a shake level (X)previously sampled (step S231). Similarly, the value of the shake level(Y) sign flag F_YDIRN indicating the sign of the present shake level (Y)is written into the shake level (Y) sign flag F_YDIRO indicating thesign of a shake level (Y) previously sampled (step S232).

Subsequently, it is determined whether or not the flag F_XBL indicatingphotography executed while moving the camera in the X-axis direction is“1” (step S233). If the flag F_XBL is “0”, the program proceeds to astep S236, which will be described later. If, on the other hand, theflag F_XBL is “1”, i.e. if photography is now being executed whilemoving the camera in the X-axis direction, it is determined that thepresent shake level (X) and an estimated shake level (X) should betreated as a predetermined level (zero level) irrespective of theoutputs of the first shake computing section 15 and the first shakeestimating/computing section 43 (step S234). In light of the fact thatphotography is now being executed while moving the camera, the time laglimit set in the time lag limit setting section 25 is changed to a lowervalue (step S235).

After that, or if it is determined at the step S233 that the flag F_XBLindicating photography executed while moving the camera in the X-axisdirection is “0”, it is determined whether or not the flag F_YBLindicating photography executed while moving the camera in the Y-axisdirection is “1” (step S236). If the flag F_YBL is “0”, the programreturns to the upper routine. On the other hand, if the flag F_YBL is“1”, i.e. if photography is now being executed while moving the camerain the Y-axis direction, it is determined that the present shake level(Y) and an estimated shake level (Y) should be treated as apredetermined level (zero level) irrespective of the outputs of thesecond shake computing section 16 and the second shakeestimating/computing section 44 (step S237). In light of the fact thatphotography is now being executed while moving the camera, the time laglimit set in the time lag limit setting section 25 is changed to a lowervalue (step S238), followed by the program returning to the upperroutine.

The processes at the steps S233-S238 are executed by the exposure startdetermination controlling section 5. By virtue of this structure, duringexecution of photography while moving the camera, exposure startdetermination is substantially executed only on the X-axis or Y-axisdirectional shake level and estimated shake level, which do not relateto the movement of the camera. As a result, a time lag which will occurduring photography can be minimized.

A detailed description will be given of the “exposure startdetermination operation B” executed at the step S124.

Referring first to the flowchart of FIG. 16, a first example of thedetermination operation B will be described.

First, it is determined, on the basis of the output of the first shakeestimating/computing section 43, whether or not the shake level (X) hascrossed the zero level (step S301). This determination is made todetermine whether or not the shake angular velocity has become ±0 inFIG. 17. If the shake level (X) is not equal to or does not cross thezero level, the program proceeds to a step S305, which will be describedlater.

If, on the other hand, the shake level (X) has crossed the zero level,an X-directional shake level flag F_XFLAG is set at “1” (step S302).Then, it is determined whether or not a Y-directional shake level flagF_YFLAG is set at “0” (step S303). This determination is made todetermine whether or not the estimated shake level (Y) has crossed thezero level (within an exposure start determination period describedlater). If the flag F_YFLAG is not “0”, i.e. if the F_YFLAG is “1” andindicates that the estimated shake level (Y) has crossed the zero level,the program proceeds to a step S314, which will be described later. Ifthe flag F_YFLAG is “0”, i.e. if the estimated shake level (Y) dose notcross the zero level, a timer for exposure start determination is resetand started (step S304).

After that, or if it is determined at the step S301 that the shake level(X) is not equal to or does not cross the zero level, it is determined,on the basis of the output of the second shake estimating/computingsection 44, whether or not the estimated shake level (Y) has crossed thezero level (step S305). This determination is made to determine whetheror not the shake angular velocity has become ±0 in FIG. 17. If theestimated shake level (Y) is not equal to or does not cross the zerolevel, the program proceeds to a step S309, which will be describedlater.

If, on the other hand, the estimated shake level (Y) has crossed thezero level, the Y-directional shake level flag F_YFLAG is set at “1”(step S306). Then, it is determined whether or not the X-directionalshake level flag F_XFLAG is set at “0” (step S307). This determinationis made to determine whether or not the estimated shake level (X) hascrossed the zero level (within an exposure start determination perioddescribed later). If the flag F_XFLAG is not “0”, i.e. if the F_XFLAG is“1” and indicates that the estimated shake level (X) has crossed thezero level, the program proceeds to the step S314 described later. Ifthe flag F_XFLAG is “0”, i.e. if the estimated shake level (X) does notcross the zero level, the timer for exposure start determination isreset and started (step S308).

After that, or if it is determined at the step S305 that the shake level(Y) is not equal to or does not cross the zero level, exposure startdetermination period information is read from the exposure startdetermination period setting section 22 (step S309). At the next stepS310, it is determined whether or not the timer having started at thestep S304 or S308 has counted a period not less than the read exposurestart determination period. This determination is made to determinewhether or not both the estimated shake levels (X) and (Y) have crossedthe zero level within the read exposure start determination period. Ifthe period counted by the timer has not yet reached the read exposurestart determination period, the program returns to the upper routine.

On the other hand, if it is determined that the period counted by thetimer has reached the read exposure start determination period, it isfurther determined that the level of shaking is high, thereby settingthe X-directional shake level flag F_XFLAG at “0” (step S311), and alsosetting the Y-directional shake level flag F_YFLAG at “0” (step S312).These flag values imply that none of the X-directional and Y-directionalshake levels has crossed the zero level. Then, the timer having startedat the step S304 or S308 is stopped (step S313), and the program returnsto the upper routine. This means that the level of shaking is not solow, or that exposure start determination, which will be describedlater, has been finished.

If it is determined at the steps S303 and S307 that the Y-directionalshake level flag F_YFLAG or the X-directional shake level flag F_XFLAGis “1”, then it is determined that exposure should be started, since thedetermination results indicate that the X-directional and Y-directionalestimated shake levels have crossed the zero level within the exposurestart determination period. Therefore, in this case, theleading-curtain-drive-start allowing flag F_GOFLAG is set at “1” (stepS314). As a result, the start of exposure is allowed at theaforementioned step S125. Thereafter, the program proceeds to the stepS313 to thereby stop the timer, and then returns to the upper routine.

In FIG. 17, at a time point T, the leading-curtain-drive-start allowingflag F_GOFLAG should be set at “1”. Further, “Δt” indicates the exposurestart determination period.

Referring now to the flowchart of FIG. 18, a second example of the“exposure start determination operation B” executed at the step S124will be described.

First, the exposure start determination level information set in theexposure start determination level setting section 23 is read (stepS321). This information corresponds to shake angular velocities “TH+”and “TH−” in FIG. 19 and indicates shake allowable limit values. Thecenter value ±0 between “TH+” and “TH−” corresponds to the zero level ofthe shake angular velocity.

On the basis of the output of the first shake estimating/computingsection 43, it is determined at a step S322 whether or not the estimatedshake level (X) falls within the range of “TH+”-“TH−”. If the level (X)falls within the range, the X-directional shake level flag F_XFLAG isset at “1” (step S323), whereas if the level (X) does not fall withinthe range, the flag F_XFLAG is set at “0” (step S324).

Subsequently, on the basis of the output of the second shakeestimating/computing section 44, it is determined at a step S325 whetheror not the estimated shake level (Y) falls within the range of“TH+”-“TH−”. If the level (Y) falls within the range, the Y-directionalshake level flag F_YFLAG is set at “1” (step S326), whereas if the level(Y) does not fall within the range, the flag F_YFLAG is set at “0” (stepS327).

After that, it is determined whether or not both the X-directional shakelevel flag F_XFLAG and the Y-directional shake level flag F_YFLAG areset at “1” (step S328). In other words, it is determined whether or notboth the estimated shake levels (X) and (Y) fall within the allowablerange of “TH+”-“TH−”. If at least one of the levels (X) and (Y) fallswithin the allowable range, the program returns to the upper routine,whereas if both the levels (X) and (Y) fall within the allowable range,the leading-curtain-drive-start allowing flag F_GOFLAG is set at “1”(step S329). As a result, the start of exposure is allowed at theaforementioned step S125. Thereafter, the program returns to the upperroutine.

In FIG. 19, at a time point T, the leading-curtain-drive-start allowingflag F_GOFLAG should be set at “1”.

A detailed description will be given of the “exposure startdetermination operation A” executed at the step S121.

Referring to the flowchart of FIG. 20, a first example of thedetermination operation A will be described. Since FIG. 20 includes thesame processes as those employed in FIG. 16 relating to thedetermination operation B, only different processes will be describedbelow.

At the step S301 or S305 in FIG. 16, determination is executed on thebasis of the estimated shake level (X) or (Y). On the other hand, at acorresponding step S401 or S405 in FIG. 20, determination is executed onthe basis of the present shake level (X) or (Y), i.e. the output of thefirst or second shake computing section 15 or 16.

The case of FIG. 20 also differs from the case of FIG. 16 in processingexecuted, at a step S403 or S407 corresponding to the step S303 or S307,when the X-directional shake level flag F_XFLAG or the Y-directionalshake level flag F_YFLAG is determined to be “1”. This processing willnow be described.

If it is determined that the X-directional shake level flag F_XFLAG orthe Y-directional shake level flag F_YFLAG is “1”, at first, the valueof a continuous shake state counter B_ZCOUNT is incremented (step S415).Then, it is determined whether or not the value of the counter B ZCOUNTis not less than a predetermined value (step S416). If the value is notless than the predetermined value, the leading-curtain-drive-startallowing flag F_GOFLAG is set at “1” (step S417), followed by theprogram proceeding to a step S414 (corresponding to the step S313 inFIG. 16). If it is determined that the value is lower than thepredetermined value, a timer for exposure start determination is resetand started at a step S418 in the same manner as at the step S304 orS308 in FIG. 16, followed by the program returning to the upper routine.

After the same determination as at the step S310 is executed at a stepS410, the same processes as at the steps S311 and S312 are executed atcorresponding steps S411 and S412, and then processing for clearing thecontents of the continuous shake state counter B_ZCOUNT is additionallyexecuted at a step S413. The reason why this processing is done is thata rather long time has elapsed after the shake level has crossed thezero level.

The above processing employed in FIG. 20 (relating to the exposure startdetermination operation A) is characterized in that the start ofexposure is allowed when the present shake levels (X) and (Y) havecrossed the zero level a plurality of times within the exposure startdetermination period. This differs from the case of FIG. 16 (relating tothe exposure start determination operation B) in which the start ofexposure is allowed when both the estimated shake levels (X) and (Y)have crossed the zero level within the exposure start determinationperiod. The structure of FIG. 20 enables execution of exposure startdetermination even if the number of shake levels to be stored for shakeestimation does not reach a predetermined value (corresponding to apredetermined period). Although in this case, it is desirable thatdetermination should be executed on the basis of an estimation result.However, this cannot actually be realized, and hence determination isexecuted under more strict conditions than usual (i.e. than thedetermination operation B).

In FIG. 21, at a time point T, the leading-curtain-drive-start allowingflag F_GOFLAG should be set at “1”. Further, “Δt” indicates the exposurestart determination period. In other words, the start of exposure isallowed when the shake levels have crossed the zero level apredetermined number of times within the exposure start determinationperiod.

Although in this embodiment, the predetermined value at the step S416 is“4”, another value may be employed. Further, the structure of FIG. 20may be modified such that the start of exposure is allowed when theshake level (X) has crossed the zero level a predetermined number oftimes within the exposure start determination period and the shake level(Y) has crossed the zero level a predetermined number of times withinthe exposure start determination period.

Referring then to the flowchart of FIG. 22, a second example of thedetermination operation A executed at the step S121 will be described.Since FIG. 22 includes the same processes as those employed in FIG. 18relating to the determination operation B, only different processes willbe described below.

At the step S322 or S325 in FIG. 18, determination is executed on thebasis of the estimated shake level (X) or (Y). On the other hand, at acorresponding step S422 or S425 in FIG. 22, determination is executed onthe basis of the present shake level (X) or (Y), i.e. the output of thefirst or second shake computing section 15 or 16.

At a step S428 corresponding to the step S328, different processes areexecuted between a case where both the X-directional shake level flagF_XFLAG and the Y-directional shake level flag F_YFLAG are “1”, and acase where at least one of the flags is not “1”. This processing willnow be described.

If it is determined that both the X-directional shake level flag F_XFLAGand the Y-directional shake level flag F_YFLAG are “1”, at first, thevalue of the continuous shake state counter B_ZCOUNT is incremented(step S429). Then, it is determined whether or not the value of thecounter B_ZCOUNT is not less than a predetermined value (step S430). Ifthe value is not less than the predetermined value, theleading-curtain-drive-start allowing flag F_GOFLAG is set at “1” (stepS431), followed by the program returning to the upper routine. If thevalue is lower than the predetermined value, the program directlyreturns to the upper routine.

On the other hand, if it is determined at the step S428 that at leastone of the X-directional shake level flag F_XFLAG and the Y-directionalshake level flag F_YFLAG is not “1”, the counter B_ZCOUNT is cleared(step S432). This is because a rather long time has elapsed after theshake level has crossed the zero level. After that, the program returnsto the upper routine.

The above processing employed in FIG. 22 (relating to the exposure startdetermination operation A) is characterized in that the start ofexposure is allowed when both the present shake levels (X) and (Y)continuously fall within a certain exposure start determination levelrange a plurality of times. This differs from the case of FIG. 18(relating to the exposure start determination operation B) in which thestart of exposure is allowed when both the estimated shake levels (X)and (Y) fall within the exposure start determination level range. Thestructure of FIG. 22 enables execution of exposure start determinationeven if the number of shake levels to be stored for shake estimationdoes not reach a predetermined value (corresponding to a predeterminedperiod). Although in this case, it is desirable that determinationshould be executed on the basis of an estimation result. However, thiscannot actually be realized, and hence determination is executed undermore strict conditions than usual (i.e. than the determination operationB).

In FIG. 23, at a time point T, the leading-curtain-drive-start allowingflag F_GOFLAG should be set at “1”. In other words, the start ofexposure is allowed when both the shake levels (X) and (Y) continuouslyfall within a certain exposure start determination level range apredetermined number of times.

Although in this embodiment, the predetermined value at the step S416 is“4”, another value may be employed.

Referring now to the flowchart of FIG. 24, a method for executing“post-exposure shake report” operation at the aforementioned step S152will be described.

First, it is determined whether or not the shake level during exposureis lower than a predetermined level A (step S501). If it is lower thanthe predetermined level A, a report pattern A is set (step S502),followed by the program proceeding to a step S506.

If, on the other hand, the shake level during exposure is not lower thanthe predetermined level A, it is then determined at a step S503 whetheror not the shake level during exposure is lower than a predeterminedlevel B. If it is lower than the predetermined level B, a report patternB is set at a step S504, followed by the program proceeding to a stepS506, which will be described later. On the other hand, if the shakelevel during exposure is not lower than the predetermined level B, areport pattern C is set at a step S505, followed by the programproceeding to the step S506 described later.

There are report patterns as shown in, for example, FIG. 11. In thiscase, the report pattern A corresponds to a pattern indicated by (a) ofFIG. 11, the report pattern B to a pattern indicated by (b) of FIG. 11,and the report pattern C to a pattern indicated by (c) of FIG. 11.

The shake level used at the step S501 or S503 corresponds to the finalshake level obtained at the aforementioned step S146. Further, thepredetermined levels A and B correspond to, for example, 50 μm and 100μm on a 35 mm film, respectively. It is sufficient if it can bediscriminated, from the report patterns, whether blurring in an imageresulting from shaking is at as low a level as can be ignored by thephotographer, or at a level as to be slightly worrying, or at as high alevel as to be significantly worrying.

After the report pattern is set, a timer for executing a post-exposureshake report for a predetermined period is started at a step S506. Afterthis, it is determined whether or not the time lag limit over flagF_OVER is set at “0” (step S507).

If the time lag limit over flag F_OVER is set at “0”, this means thatthere is no over time lag, i.e. that exposure has been started aftershaking has been reduced, and therefore the state reporting section 66is lit in the form of the report pattern set at the step S502, S504 orS505 (step S508).

On the other hand, if the time lag limit over flag F_OVER is set at “1”,this means that there is an over time lag, i.e. that exposure has beenstarted so the photographer will not misunderstand that the camera isout of order, although shaking has not yet been reduced. In this case,the state reporting section 66 is blinked in the form of the reportpattern set at the step S502, S504 or S505 (step S509). This blinkinginforms the photographer that exposure has been started after a time laglimit (i.e. exposure has been executed with a high level of shaking),which means that photography has been executed at a time point differentfrom the photographer's target time point and therefore that it ishighly possible that blurring occurs in a photograph.

After starting the lighting or blinking of the state reporting section,it is determined at a step S510 whether or not the report period timerhaving started at the step S506 has counted a predetermined period. Ifit is determined that the predetermined period has not yet elapsed, theprogram returns to the step S507. The predetermined period is, forexample, 300 mSEC.

After the predetermined period elapses, the post-exposure shake reportby the state reporting section 66 is turned off (step S511), followed bythe program returning to the upper routine.

Although the present invention has been described with reference to anembodiment thereof, it is not limited to the embodiment, but may bemodified in various manners without departing from its scope.

For example, in the above embodiment, one of two exposure startdetermining methods is selectively used for exposure startdetermination, on the basis of the value of the counter B_COUNTA forcounting the number of data items accumulated for shake estimation andcomputation. However, instead of the two exposure start determiningmethods, three or more exposure start determining methods may be used.Further, the exposure start determining method may be selected on thebasis of, for example, a predetermined time point as well as the valueof the counter B_COUNTA.

Moreover, although the embodiment relates to a single-lens reflexcamera, the invention is not limited to this type of camera.

In addition, the invention is also applicable to a so-called digitalcamera, which picks up an image of a to-be-photographed object using animaging element and stores the image in a storage medium.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details, representative devices, andillustrated examples shown and described herein. Accordingly, variousmodifications may be made without departing from the spirit or scope ofthe general inventive concept as defined by the appended claims andtheir equivalents.

What is claimed is:
 1. A camera with a blur reducing function,comprising: shake detecting/computing means for detecting and computinga shake state of the camera; exposure start determining means forexecuting exposure start determination to reduce shaking duringexposure, on the basis of an output of said shake detecting/computingmeans; exposure means for executing an exposure operation in accordancewith a determination result of said exposure start determining means;exposure-start-determining-method changing means for changing anexposure start determination method used in said exposure startdetermining means; and condition setting means for setting a conditionused in said exposure-start-determining-method changing means forchanging the exposure start determination method used in said exposurestart determining means; wherein said condition setting means includescamera control means for controlling all operations of the camera, andsaid exposure-start-determining-method changing means changes theexposure start determination method used in said exposure startdetermining means in response to an instruction from said camera controlmeans; and wherein said exposure start determining means uses differentexposure start determination methods for the output of said shakedetecting/computing means and for an output obtained by estimation basedon the output of said shake detecting/computing means.
 2. A camera witha blur reducing function, comprising: shake detecting/computing meansfor detecting and computing a shake state of the camera; exposure startdetermining means for executing exposure start determination to reduceshaking during exposure, on the basis of an output of said shakedetecting/computing means; exposure means for executing an exposureoperation in accordance with a determination result of said exposurestart determining means; exposure-start-determining-method changingmeans for changing an exposure start determination method used in saidexposure start determining means; and condition setting means forsetting a condition used in said exposure-start-determining-methodchanging means for changing the exposure start determination method usedin said exposure start determining means; wherein said condition settingmeans includes camera control means for controlling all operations ofthe camera, and said exposure-start-determining-method changing meanschanges the exposure start determination method used in said exposurestart determining means in response to an instruction from said cameracontrol means, and wherein said exposure-start-determining-methodchanging means changes an exposure start determination algorithm used insaid exposure start determining means.
 3. A camera with a blur reducingfunction, comprising: shake detecting/computing means for detecting andcomputing a shake state of the camera; exposure start determining meansfor executing exposure start determination to reduce shaking duringexposure, on the basis of an output of said shake detecting/computingmeans; exposure means for executing an exposure operation in accordancewith a determination result of said exposure start determining means;exposure-start-determining-method changing means for changing anexposure start determination method used in said exposure startdetermining means; and condition setting means for setting a conditionused in said exposure-start-determining-method changing means forchanging the exposure start determination method used in said exposurestart determining means; wherein said condition setting means includes“photography-with-moving-camera” determining means for determiningwhether or not photography is being executed while moving the camera,and wherein said exposure-start-determining-method changing meanschanges the exposure start determination method used in said exposurestart determining means, in response to an output from said“photography-with-moving-camera” determining means.
 4. The cameraaccording to claim 3, wherein said “photography-with-moving-camera”determining means determines whether or not photography is beingexecuted while moving the camera, on the basis of said shake statedetected by the shake detecting/computing means.
 5. The camera accordingto claim 3, wherein said exposure-start-determining-method changingmeans changes the output of said shake detecting/computing means to apredetermined value when said “photography-with-moving-camera”determining means determines that photography is being executed whilemoving the camera.
 6. The camera according to claim 3, wherein said“photography-with-moving-camera” determining means determines whether ornot photography is being executed while moving the camera, on the basisof a level of shaking in each of two directions perpendicular to aphotography optical axis of the camera and intersecting each other, andsaid exposure-start-determining-method changing means changes the outputof said shake detecting/computing means to a predetermined value, theoutput corresponding to that one of the two directions in whichphotography is determined to be being executed while moving the camera.7. The camera according to claim 3, wherein said exposure startdetermining means finishes exposure start determination based on theoutput of said shake detecting/computing means and starts the exposureoperation of said exposure means irrespective of a shake state of thecamera, when a time limit set by said exposure-start-determining-methodchanging means has expired, and said exposure-start-determining-methodchanging means changes the time limit when said“photography-with-moving-camera” determining means determines thatphotography is being executed while moving the camera.
 8. A camera witha blur reducing function, comprising: shake detecting/computing meansfor detecting and computing a shake state of the camera; exposure startdetermining means for executing exposure start determination to reduceshaking during exposure, on the basis of an output of said shakedetecting/computing means; exposure means for executing an exposureoperation in accordance with a determination result of said exposurestart determining means; exposure-start-determining-method changingmeans for changing an exposure start determination method used in saidexposure start determining means; and condition setting means forsetting a condition used in said exposure-start-determining-methodchanging means for changing the exposure start determination method usedin said exposure start determining means; wherein said condition settingmeans includes time lag measuring means for measuring a time lag bywhich said exposure start determining means retards an operation of saidexposure means, and wherein said exposure-start-determining-methodchanging means changes the exposure start determination method used insaid exposure start determining means, in accordance with an output fromsaid time lag measuring means.
 9. The camera according to claim 8,wherein said shake detecting/computing means detects a shake level ineach of two directions substantially perpendicular to a photographyoptical axis of the camera and intersecting each other, and saidexposure-start-determining-method changing means changes determinationperiod information indicating a determination period required todetermine whether or not both the shake levels in the two directionsreach a predetermined value.
 10. The camera according to claim 8,wherein said exposure-start-determining-method changing means changesdetermination level information indicating a determination level, on thebasis of which the output of said shake detecting/computing means isdetermined.
 11. A camera with a blur reducing function, comprising:shake detecting/computing means for detecting and computing a shakestate of the camera; shake estimating means for storing an output ofsaid shake detecting/computing means and estimating a level of shakingon the basis of the stored output; shake information stored statemonitoring means for monitoring a shake information stored state of saidshake estimating means; exposure start determining means for executingexposure start determination to reduce shaking during exposure, on thebasis of an output of said shake detecting/computing means or an outputof said shake estimating means; exposure means for executing an exposureoperation in accordance with a determination result of said exposurestart determining means; and exposure-start-determining-method changingmeans for changing an exposure start determination method used in saidexposure start determining means, on the basis of a monitoring result ofsaid shake information stored state monitoring means.
 12. The cameraaccording to claim 11, wherein said exposure start determining meansuses different exposure start determination methods for the output ofsaid shake detecting/computing means and for the output of said shakeestimating means.
 13. The camera according to claim 11, wherein saidexposure-start-determining-method changing means changes an exposurestart determination algorithm used in said exposure start determiningmeans.
 14. A camera with a blur reducing function, comprising: a shakedetecting section for sampling shake levels of the camera in a timeseries manner; a computing section for receiving a predetermined numberof shake data items sampled by said shake detecting section in the timeseries manner, and executing predetermined computation of the shake dataitems; and a photography start timing determining section for comparinglatest shake data, output from said shake detecting section, with afirst determination reference range, and comparing a computation result,when output 20- from said computing section, with a second referencerange different from the first reference range, thereby determining onthe basis of comparison results whether or not photography should bestarted.
 15. The camera according to claim 14, wherein the firstdetermination reference range has a narrower determination allowancewidth than the second determination reference range.
 16. A camera with ablur reducing function including a shake detecting section forrepeatedly detecting a shake state of the camera, and in which a shakestate of the camera is repeatedly detected in response to a releasingoperation for instructing start of photography, and photography isstarted at a time point at which shaking is in a predetermined state,comprising: a determination reference range setting section for settingfirst and second reference ranges which are different from each other; ashake estimating section for estimating a shake state of the camera tobe obtained after a predetermined period, on the basis of apredetermined number of shake data items detected by said shakedetecting section; and a photography start timing determining sectionfor comparing latest shake data, output from said shake detectingsection, with a first determination reference range until estimationinformation is output form said shake estimating section, and comparingthe estimation information with the second reference range when theestimation information is output, thereby determining on the basis ofcomparison results whether or not photography should be started.
 17. Thecamera according to claim 16, wherein the first determination referencerange has a narrower determination allowance width than the seconddetermination reference range.
 18. A camera with a blur reducingfunction, comprising: a shake data sampling section, responsive to areleasing operation, for sampling, in a time series manner, a shakelevel in each of two directions perpendicular to a photography opticalaxis of the camera and intersecting each other; a“photography-with-moving-camera” determining section for determining, onthe basis of an output of said shake data sampling section, whether ornot photography is being executed while moving the camera, andinvalidating data which is included in the output of said shake datasampling section and concerns a direction in which the camera is moving;and a control section for starting photography when the output of saidshake data sampling section satisfies a predetermined reference value,or when a predetermined period has elapsed after the releasingoperation.
 19. The camera according to claim 18, wherein said controlsection changes the predetermined period to a shorter period when said“photography-with-moving-camera” determining section determines thatphotography is being executed while moving the camera.
 20. A camera fordetecting levels of shaking in a plurality of directions in response toa releasing operation, and starting photography at a time point at whichshaking is at a low level, comprising: a shake level detecting,responsive to a releasing operation, for detecting levels of shaking ina plurality of directions; and a control section for determining, on thebasis of levels of shaking in the plurality of directions detected bysaid shake level detecting section, whether or not photography is beingexecuted while moving the camera, the control section invalidating ashake state signal obtained in a direction in which photography is beingexecuted while moving the camera.
 21. A camera with a blur reducingfunction, comprising: a time measuring section, responsive to areleasing operation, for starting to measure a time period and stop itwhen a predetermined time limit expires; a shake detecting section forrepeatedly detecting a shake level of the camera; and a photographystart timing determining section for starting photography, when thepredetermined time limit has expired or while time measurement isexecuted before the predetermined time limit expires, in accordance witha comparison result between a predetermined reference range and anestimated level of shaking which is obtained, after a predeterminedperiod, on the basis of a plurality of shake data items including thedetected shake level and shake levels near the detected shake level,wherein said photography start timing determining section increases thepredetermined period each time comparison has been executed.
 22. Acamera with a blur reducing function, comprising: a time measuringsection, responsive to a releasing operation, for starting to measure atime period and stop it when a predetermined time limit expires; a shakedetecting section for repeatedly detecting a shake level of the camera;and a photography start timing determining section for startingphotography, when the predetermined time limit has expired or while timemeasurement is executed before the predetermined time limit expires, inaccordance with a comparison result between a predetermined referencerange and an estimated level of shaking which is obtained, after apredetermined period, on the basis of a plurality of shake data itemsincluding the detected shake level and shake levels near the detectedshake level, wherein said photography start timing determining sectionwidens the predetermined reference range each time comparison isexecuted.
 23. A method of reducing blurring in a photograph taken by acamera which has a sensor for detecting a shake state of the camera andcan reduce shaking during exposure, comprising: a first step of samplinglevels of shaking in a time series manner on the basis of an output ofthe sensor; a second step of receiving a predetermined number of shakedata items sampled in the time series manner, thereby executingpredetermined computation of the shake data items; a third step ofcomparing latest shake data, output from the sensor, with a firstdetermination reference range; a fourth step of comparing a computationresult, when output at said second step, with a second determinationreference range different from the first determination reference range;and a fifth step of determining, on the basis of a comparison result atsaid third step or said fourth step, whether or not exposure should bestarted.
 24. The method according to claim 23, wherein the firstdetermination reference range has a narrower determination allowancewidth than the second determination reference range.